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Abstract

Currently, there is little known about stink bug (Hemiptera: Pentatomidae) eggs,
their natural enemies, and their susceptibility to insecticides.
A survey of stink bug egg parasitoids was conducted in row crops and vegetables
in eastern Virginia. Parasitization was highest in Euschistus servus (Say) with 89.7% and
49.2% of egg masses and individual eggs parasitized, respectively, followed by
Acrosternum hilare (Say), with nearly half of all individual eggs parasitized. The most
common parasitoid was Telenomus podisi Ashmead (Hymenoptera: Scelionidae).
Laboratory egg-dip bioassays and field applications of acephate, lambda-cyhalothrin,
spinosad, and thiamethoxam, were carried out to determine efficacy against nonparasitized
E. servus and A. hilare eggs, and T. podisi embryos developing in E. servus
eggs. Results showed that eggs of both species were susceptible to insecticides, that there
was little difference among insecticides, but there was generally greater mortality in
field-treated versus dipped eggs. Developing T. podisi were generally more susceptible
to insecticides than stink bugs.
Scanning electron microscopy was used to investigate oviposition sites as possible
sites of insecticide movement into eggs. Oviposition wounds and holes made by a
tungsten probe were similarly sealed by a â scabâ , so it was not clear whether these
wounds allow for increased insecticide movement into parasitized eggs.
Differences in chorion permeability of non-parasitized and parasitized eggs were
compared by immersing them in solutions containing different 14C-ammended
insecticides at field application rates for 0, 30, 120 or 240 minutes. Results showed that
insecticide movement into the egg increased significantly with immersion time for both
acephate and lambda-cyhalothrin, but there were no significant differences between nonparasitized
and parasitized eggs. Neither immersion time nor egg status was significant
for thiamethoxam. A model was constructed that predicts amount of insecticide entering
the egg at any given time.
An 8-week survey for the brown marmorated stink bug, Halyomorpha halys (StÃ¥l)
was conducted in Beijing and five other cities in China. Incidence of egg parasitism was
recorded. Results showed that H. halys utilized at least four different plants throughout
the summer, and insects were found in Nanjing, Kunming, and Xiâ an. Parasitization of
eggs was noted, and the parasitoids were identified as Trissolcus halyomorphae Yang
(Scelionidae: Hymenoptera) by K.A. Hoelmer (USDA-ARS).